<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    const arr = [{
      name: '张三',
      salary: 10000
    }, {
      name: '李四',
      salary: 10000
    }, {
      name: '王五',
      salary: 20000
    },
    ]
   const res= arr.reduce(function (prev, item) {
      return prev + item.salary*0.3
    },0)
    console.log(res);
  </script>
</body>

</html>